iSCSI, which stands for Internet Small Computer System Interface, generally refers to a transport layer protocol that works on top of the Transport Control Protocol (TCP) and allows the SCSI command to be sent end-to-end over local-area networks (LANs), wide-area networks (WANs), or the Internet. iSCSI can transport block-level data between an iSCSI initiator on a server and an iSCSI target on a storage device. The iSCSI protocol can encapsulate SCSI commands and assemble the data in packets for the TCP/IP layer. Packets are sent over the network using a point-to-point connection. Upon arrival, the iSCSI protocol disassembles the packets, separating the SCSI commands so the operating system (OS) can see the storage as a local SCSI device. Some SCSI commands utilize additional parameter data to accompany the SCSI command. Such client data is normally sent in a separate PDU, but can also be placed within the same protocol data unit (PDU) as the SCSI I/O command for improving performance, and is generally referred to as immediate data.